CN112513604A

CN112513604A - Density monitor with integrated low pressure indicator

Info

Publication number: CN112513604A
Application number: CN201980030078.9A
Authority: CN
Inventors: 雷莫·哈尔比尔; 阿希姆·帕尔克
Original assignee: TRAFAG AG
Current assignee: TRAFAG AG
Priority date: 2018-04-03
Filing date: 2019-03-22
Publication date: 2021-03-16
Also published as: US20210148801A1; DE102018107852A1; DE102018107852B4; US11573163B2; WO2019192857A1

Abstract

The invention relates to a density monitor (10) for monitoring the density of a gas in a gas chamber (20). The density monitor (10) includes a measuring device (12) having a first measuring device (24) and a second measuring device (28), the two measuring devices (24; 28) being connected together. The first measuring device (24) is designed to measure a first pressure range (62) relative to the atmosphere, and the second measuring device (28) is designed to measure an absolute second pressure range (64). The density monitor (10) further comprises an indicating device (50) designed to indicate the two pressure ranges (24; 28). The density monitor (10) further comprises a movable drive element (48) designed to drive the indicator device (50), wherein at least one of the two measuring devices (24; 28) is designed to move the drive element (48) to drive the indicator device (50), wherein the indicator device (50) comprises an indicator element (58) designed to indicate the two pressure ranges (62, 64).

Description

Density monitor with integrated low pressure indicator

Technical Field

The present invention relates to a density monitor for monitoring the density of a gas in a gas cell.

Background

For example, from Trafagg company "SF₆Gas monitoring "and printed note H7643b of month 10 2011 are known for such density monitors. In this case, a separating element is arranged on the measuring bellows, in the interior of which a reference volume is present. One end of the measuring bellows is fixed and the separating element is arranged at the other end of the measuring bellows. This will cause the separation element to move if the pressure in said gas volume increases with respect to the reference volume. A drive element in the form of a drive tappet is fixed to the separating element, which acts as an indicator element of the indicator device to actuate a pointer that moves relative to the scale. The pointer indicates the corresponding gas density.

As is known from the above publication, density monitors are used in particular for monitoring the insulating gas (usually SF) of gas-insulated switchgear₆) The density of (c). The main task is to closely monitor and display the temperature compensated fill pressure of the system. This is achieved by an accurate reference chamber measuring mechanism and an associated high resolution reference scale. However, this has the disadvantage of limiting the measurement range due to the high resolution.

If a lower pressure range is required for the measurement, e.g. for transport or the like, than indicated by the high resolution main scale in the gas chamber to be monitored, an additional measuring mechanism with a lower resolution has to be provided.

Disclosure of Invention

It is an object of the present invention to provide a density monitor which allows a wider range of applications.

This object is achieved by a density monitor for monitoring the density of a gas in a gas cell. Advantageous embodiments of the invention with useful and non-effective further developments are specified in the dependent claims.

The present invention provides a density monitor for monitoring the density of a gas in a gas cell. The density monitor includes a measurement device having a first measurement device and a second measurement device, wherein the first measurement device and the second measurement device are coupled together. The first measuring device is arranged to measure a first pressure range with respect to the atmosphere. The term "relative" especially means measuring relative pressure. In the case of relative pressure, the pressure is measured relative to the pressure of the atmosphere or environment (in particular the air pressure). The average atmospheric pressure at sea level is 1013.25 mbar. The first pressure range is preferably a low pressure range. For example, the low pressure range includes pressure values between-300 and 620 kPa. The term "measuring a first pressure range" especially means that the first measuring device is configured to record pressure values or pressures within the first pressure range. The second measuring device is configured to measure a second pressure range, which is higher in absolute value than the first pressure range. The term "measuring a second pressure range" especially means that the second measuring device is configured to record pressure values or pressures within the second pressure range. Preferably, the second pressure range is the operating pressure range or the high pressure range. For example, the operating pressure range includes pressure values between 620kPa and above 700 kPa. In particular, the two measuring devices (first measuring device and second measuring device) are coupled together or connected to one another in such a way that a first pressure range can be measured or recorded with respect to the atmosphere and thereafter a second pressure range can be measured or recorded continuously or sequentially in absolute values. The term "absolute" refers to measuring absolute pressure. The absolute pressure is in particular a pressure relative to the pressure in vacuum (zero pressure). The density monitor also includes an indicating device configured to indicate the first pressure range and the second pressure range. Furthermore, the density monitor comprises a movable drive element which is designed to drive or control the indicating device, wherein at least one of the two measuring devices is configured to move the drive element in order to drive the indicating device. Furthermore, the indicating device comprises an indicating element which is designed to indicate the two pressure ranges. Preferably, the drive element acts on the indicator device to move the indicator element. The pointer may be arranged on a display area comprising scales indicating two pressure ranges. The pointer is movable relative to the scale to indicate the pressure range. For this purpose, the indicating device may comprise a measuring mechanism. The drive element can act on a measuring mechanism of the indicating device such that the pointer can be moved, in particular in dependence on the measured or recorded pressure.

By coupling the first and second measuring devices together, two pressure ranges (a first pressure range and a second pressure range) can be indicated or shown on the same indicating device. Therefore, no additional indicating means are required. Furthermore, by coupling together two measuring devices (a first measuring device and a second measuring device), it is possible to record two pressure ranges that differ from one another and indicate them with a single indicating device. The density monitor therefore has a particularly high resolution and a particularly wide measuring range, which makes the range of applications of the density monitor particularly wide.

An advantageous embodiment provides that the second measuring device is designed to measure the second pressure range in a temperature-compensated manner. The term "measuring" particularly means determining or detecting or recording. The term "temperature compensation" is understood in particular as a measure which counteracts the effect of undesired temperatures, in particular with the aim that a change in temperature does not lead to a change in the reaction of the density monitor or to a destruction of the density monitor. The term "temperature compensation" particularly refers to a temperature compensation zone. The temperature compensation zone is in particular a temperature zone for which a temperature error or temperature coefficient applies. Temperature compensation allows the density monitor to operate particularly accurately and reliably.

One preferred design of the density monitor comprises an indicating device which is drivable by the drive element and which comprises an indicating element which is movable relative to a display area of the indicating device. The scale preferably shows a first pressure range and in particular a second pressure range adjacent to the first pressure range. The drive element and the indicator element are arranged and/or designed in such a way that the indicator element is located between the low-pressure region and the high-pressure region when the stop is grasped and released.

A further advantageous embodiment provides that the indication means further comprise a display area provided with characters and/or graduations, the indication elements and/or characters and/or graduations comprising phosphorescent or fluorescent material. In other words, the indication elements and/or the characters and/or the scale may be formed by phosphorescent or fluorescent materials. The term "phosphorescence" is especially the afterglow property of a substance in the dark after irradiation with visible UV light. Phosphorescent materials may generally be crystals having a small mixture of foreign substances that disturb the crystal lattice structure. It is common to use sulphides of the second group of metals together with zinc and to add small amounts of heavy metal salts, for example zinc sulphide with trace amounts of heavy metal salts. The term "fluorescence" especially refers to the spontaneous emission of light shortly after excitation of a substance by an electronic transition. Fluorescence and phosphorescence are both forms of luminescence, also known as luminescence, which are photophysical processes. Fluorescence is particularly characterized by its rapid cessation, primarily in milliseconds, after the end of irradiation. In the case of phosphorescence, on the other hand, afterglow may last from a few seconds to several hours. The phosphorescent or fluorescent material in particular improves the readability of the indicating means, thereby improving the reliability of the density monitor.

Advantageously, the second measuring device has a second movable separating element which is designed to separate a closed reference volume to be filled with the reference pressure from the gas chamber, said second separating element being arranged on a second measuring bellows which separates the reference volume from the gas chamber. In a corresponding manner, the second measuring device can also be referred to as a reference chamber measuring mechanism. For example, the second separating element can be designed as a separating wall, in particular as a movable separating wall. The term "bellows" particularly refers to a tube made of a predetermined material, which is collapsible or foldable in an accordion manner. The term "movable" especially means that the second separating element is held or supported in a slidable or movable manner.

An advantageous development provides that the first measuring device comprises a first movable separating element which is configured to separate the gas chamber from the further space, the first movable separating element being arranged on a first measuring bellows which separates the gas chamber from the further space, and the first separating element and the second separating element being movable relative to one another and being limited by a stop, so that one separating element is movable relative to the other separating element to an extent limited by the stop. For example, the first separating element and the second separating element can be designed as separating walls, in particular as movable separating walls. The term "bellows" particularly refers to a tube made of a predetermined material, which can be contracted or folded in an accordion manner. The term "movable" especially means that the second separating element is held or supported in a slidable or movable manner. The term "space" particularly refers to a predefined or delimited area or a volume having a delimitation or a predefined extension. The term "stop" especially refers to a position where an object can be moved or displaced. This stop has the advantage that the first measuring device and the second measuring device can be coupled together particularly simply and reliably, in particular mechanically.

Preferably, the drive element is coupled to the first or second movable separation element for common movement. Particularly preferably, the stop limits the movement of the first movable partition element and the coupled second drive element relative to the second movable partition element. By arranging the drive element on one of the two separating elements or coupling the drive element to one of the two separating elements, the drive element can be moved particularly easily and reliably.

Advantageously, the second movable separating element is arranged on a second measuring bellows which separates the reference volume from the gas chamber, and/or the first movable separating element is arranged on a first measuring bellows which separates the gas chamber from a further space or a further chamber. Particularly preferably, the first measuring bellows and the second measuring bellows are arranged concentrically with respect to one another. Preferably, the reference pressure in the reference volume is higher than the pressure in the further space and/or the ambient pressure of the further space.

Preferably, the second measurement bellows comprises an outer bellows and an inner bellows, which define a reference volume therebetween. In other words, the second measurement bellows may enclose the reference volume. Preferably, the first measuring bellows is arranged within an inner bellows of the second measuring bellows. In other words, the first measuring bellows is preferably surrounded by the second measuring bellows, in particular by the inner bellows of the second measuring bellows. This arrangement has the advantage that, on the one hand, the coupling of the first measuring device and the second measuring device is particularly simplified and, on the other hand, the size of the measuring device can be reduced.

Preferably, the drive element comprises a drive tappet which drives or moves an indicator element, in particular a pointer, of the indicator device. In other words, the drive element can act on the pointer in such a way that a rotation of the pointer can be effected or carried out as a result. Furthermore, the drive tappet or the drive element can be arranged inside the first measuring bellows and/or inside the second measuring bellows. In other words, the drive tappet or the drive element can be accommodated in the first and/or the second measuring bellows.

An advantageous and in particular alternative embodiment provides that the first measuring device has a pressure membrane for measuring the first pressure range. Preferably, the pressure membrane is designed to drive the indicating means, in particular by the stroke of the pressure membrane. In other words, the stroke of the pressure membrane may be used to actuate the indicating means. In particular, the pressure membrane acts on a movable drive element in order to drive the indicator device. The term "pressure membrane" is understood to mean, in particular, a flexible or elastic membrane. The "film" is preferably a two-dimensional or thin layer of material that is subjected to tensile or compressive forces. The pressure membrane allows a particularly easy and reliable recording of the first pressure range. The pressure membrane is preferably coupled to or provided on a second separating element, which may also be referred to as reference chamber bottom. Additionally or alternatively, the pressure membrane may be arranged on a first separating element, which may also be referred to as a low-pressure bottom.

Advantageously and in particular, in an alternative embodiment, the first measuring means comprise a tubular spring for measuring the first pressure range. In other words, the first measuring device may also be referred to as a tubular spring measuring mechanism. The term "tubular spring" particularly refers to a measuring element for measuring a pressure difference. In particular, the tubular spring is a flat metal tube wound in a circular, spiral or helical manner. When pressure is applied to the spring, the spring tends to flex open. For example, a change in the stroke of the spring end of the tubular spring can be transmitted to the measuring mechanism by the pull rod and can be converted into a rotation of the pointer shaft. Preferably, the pinion of the indicating device is coupled to the tubular spring such that when the first pressure range is measured, a radial movement is transmitted to the indicating device and this radial movement is converted into a rotational movement of the pointer in order to indicate the first pressure range. Preferably, the pinion of the measuring means is connected to the tubular spring. This allows the radial movement to be transmitted to the measuring mechanism in the low pressure range, in particular in the first pressure range, which radial movement is then converted into a rotational movement of the pointer. A "pinion" is understood to mean a gear which drives another gear, in particular a larger gear than the pinion.

Preferably, the tubular spring is in particular fluidly coupled to the gas chamber. The tubular spring may be coupled or linked or connected to the gas chamber, e.g. via a channel. In particular, the tubular spring or the channel is arranged partially inside the gas chamber. By being at least partially arranged inside the gas chamber, the tubular spring is adapted to register one or more pressures or pressure changes of the first pressure range.

An advantageous and in particular alternative embodiment provides that the first measuring means comprise a pressure cell for measuring the first pressure range. The pressure cell or pressure membrane may also be referred to as a aneroid barometer. In a liquid-free barometer, a pot-shaped hollow body made of a metal plate, in particular a thin metal plate, can be deformed by pressure. A predetermined pressure exists in the can which compensates for the change in the modulus of elasticity of the metal sheet by temperature. This deformation is transmitted to the drive element by the mechanism, the deformation being compression when the pressure rises and expansion when the pressure falls. The indicating device preferably comprises a transmission element configured to receive the vertical movement of the aneroid barometer and to convert the vertical movement into a rotational movement of the indicating element to indicate the first pressure range. The transmission element is designed, for example, as a pin. In an advantageous manner, the measuring mechanism can receive vertical movements via two pins and can convert these vertical movements into a rotational movement of the pointer. In this case, one pin may be assigned to the aneroid barometer and an additional pin may be assigned to the drive element. Preferably, the aneroid barometer is coupled, in particular fluidically coupled, with the gas chamber. For example, the aneroid barometer may be coupled or linked to the gas chamber via a channel. In particular, the aneroid barometer or channel is arranged partially inside the gas chamber. By this partial arrangement of the aneroid barometer within the gas chamber, the aneroid barometer is adapted to register a pressure or a plurality of pressures or pressure changes of the first pressure range.

The preferred design of the density monitor creates a measuring device with which, on the one hand, the density of the gas in the gas chamber can be monitored with high resolution and high accuracy during operation of the switchgear, and, on the other hand, additional pressure ranges, in particular low pressure ranges, can be monitored, for example during transport or filling of the switchgear.

This is preferably done with a reliable mechanical device having a simple construction. In particular, both the low pressure range and the higher pressure range can be indicated by a common indicator element.

The invention also comprises a measuring device comprising a first measuring device and a second measuring device, wherein the first measuring device and the second measuring device are in particular mechanically coupled together. The first measuring device is designed for measuring a first pressure range relative to the atmosphere. The second measuring device is designed to measure a second pressure range, which is higher in absolute value than the first pressure range.

The invention also comprises a further development of the measuring device according to the invention. These further developments comprise features which have been described in the context of the further developments of the density monitor according to the invention, and the description thereof will not be repeated.

Drawings

An exemplary embodiment of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 is a schematic diagram of a preferred design of a density monitor;

FIG. 2 shows an enlarged detail of a measuring device of the density monitor of FIG. 1 comprising a first measuring device and a second measuring device;

FIG. 3 shows the measuring device of FIG. 2, showing a space in communication with a gas chamber of a switchgear to be monitored;

FIG. 4 shows the measurement device of FIG. 2 with the reference volume highlighted;

FIG. 5 shows the measuring device of FIG. 2, highlighting the first measuring device for low pressure measurement;

FIG. 6 is a schematic diagram of another preferred design of a density monitor;

FIG. 7 is a schematic diagram of yet another preferred design of a density monitor; and

FIG. 8 is a schematic diagram of another preferred design of the density monitor.

Detailed Description

The design examples described below represent preferred embodiments of the present invention. In the design examples, the components of the embodiments described each represent a respective feature of the invention, which are considered independently of one another and constitute a further development of the invention, and which are therefore also independent of one another and are therefore part of the invention, either individually or in different combinations than those illustrated. Furthermore, the described embodiments can also be supplemented by other features of the invention which have been described above.

Elements in the drawings that are similar or have similar functions are identified by the same reference numerals.

FIG. 1 illustrates one embodiment of a density monitor 10 that includes a measurement device 12. The measuring device 12 is shown once again on an enlarged scale in fig. 2.

The density monitor 10 has a system side pressure connection 14 for connection to a system 16. The system 16 will be filled with gas and its gas density must be monitored. The system 16 is, for example, a high-voltage switching system, a high-voltage converter, a high-voltage line, a switchgear and/or a transformer. There is system gas 18 in the system 16, the system gas 18 being in fluid communication via the pressure connection 14 with a system gas chamber or gas chamber 20 in the housing of the density monitor 10, which may also be referred to as a sensor housing 22. In other words, the system 16 and the gas chamber 20 are fluidly connected to each other via said pressure connection 14.

The measuring device 12 is at least partially (this means completely or partially) accommodated or received in the sensor housing 22. The measuring device 12 comprises a first measuring device 24, which is highlighted in fig. 5, and a second measuring device 28, which is highlighted in fig. 4. The second measuring device 28 is filled with a reference gas 26. The first measuring device 24 is designed to measure a first pressure range, in particular in a relative sense. The second measuring device 28 is configured to measure the second pressure range, in particular in absolute value and/or in a temperature-compensated manner.

The second measuring device 28 comprises a second measuring bellows 30. The second measuring bellows 30 is fixed at one end, here to the reference chamber cover 32. The second measuring bellows 30 has a reference chamber bottom 34 on its other end. The reference chamber bottom 34 may be formed as a second partition element 35, in particular as a second partition wall.

The second measurement bellows 30 has an outer bellows 36 and an inner bellows 38. The outer bellows 36, the inner bellows 38, the reference chamber bottom 34 serving as the second partition element 35, and the reference chamber cover 32 enclose a reference chamber or reference space as a reference volume to be filled with a predetermined reference pressure of the reference gas 26.

In a corresponding manner, the second measuring device 28 can also be referred to as a reference chamber measuring mechanism.

The first measuring device 24 has a first measuring bellows 40. The first measuring bellows 40 is designed in particular as a low-pressure bellows 42.

The first measuring bellows 40 is arranged concentrically with the second measuring bellows 30. In other words, the second measurement bellows 30 may surround the first measurement bellows 40. In particular, a low pressure bellows 42 is disposed within the inner bellows 38. At one end, the first measuring bellows 40 is also fixed, for example in the region of the reference chamber cover 32.

At the other end, the first measuring bellows 40 comprises a low-pressure bottom 46, which is in particular movable, designed as a first separating element 44. The first separating element 44 is coupled to a drive element 48, the movement of the drive element 48 being transmitted to the indicating device 50 via a transmission.

In the embodiment shown, the drive element 48 comprises a drive tappet, for example in the form of a switch lever. In this way, the drive element 48 is coupled to the first movable partition element 44 for a joint movement.

The second separating element 35 formed by the reference chamber bottom 34 and the first separating element 44 formed by the low-pressure bottom 46 can be moved to a limited extent relative to each other. This movement is limited in one direction by the upper stop 52 and in the other direction by an additional stop, for example in the form of a driver 54. When moved upwards in fig. 2, the first movable partition element 44 can be moved along the drive element 48 (e.g. a switch lever) by means of the drive 54.

The switch lever is designed in the same way as disclosed in the company manual "SF 6 gas monitoring" by TrafagAG ag mentioned at the outset. Accordingly, a switch lever in the density monitor housing 56 (manometer housing) can actuate a switch (not shown) as it moves. Furthermore, the switch lever is able to actuate the indicating means 50 by moving the pointer 58 of the indicating means 50 over a display area provided with a scale 60.

The scale 60 has a first pressure range 62 and a second pressure range 64, the first pressure range 62 being designed as a low pressure indicator and the second pressure range 64 being designed as a high resolution main scale or a high pressure indicator. The first pressure range 62 and the second pressure range 64 are arranged side by side, in particular adjacent to one another.

The indicator elements 58 (i.e., the pointer) and/or the characters on the display area and/or the characters on the scale 60 comprise phosphorescent or fluorescent materials. In other words, the indicator element 58 (i.e., the pointer) and/or the characters and/or graduations on the display area may be made of a phosphorescent or fluorescent material.

Thus, the density monitor 10 is designed for monitoring the gas density in the gas chamber 20 (in fluid communication with the system 16) and comprises a first movable separation element 44 and a second movable separation element 35. The second movable partition element 35 separates a closed reference volume (see fig. 4) to be filled with the reference gas 26 at a predetermined reference pressure from the gas chamber 20 highlighted in fig. 3. The second movable partition element 44 separates the gas chamber 20 from another space. The further space may be open to the environment and thus at ambient pressure.

The first separating element 44 can be moved to a limited extent relative to the second separating element 35. The relative movement is limited by at least one

stop

52, 54. The drive element 48 of the mechanically driven indication means 50 is coupled to one of the separating elements, in this case to the first separating element 35.

The operation of the density monitor 10 will be described in more detail below.

In order to continuously present the entire pressure range (first pressure range 62 and second pressure range 64) via the scale 60 and the pointer 58, two measuring

devices

24, 28 are provided (see fig. 2).

The two

measuring devices

24, 28 are actuated one after the other. This range is derived from the indication of the depression of the first pressure range 62 by the actuation of the first measuring device 24 via the indication of the second pressure range 64 by the particularly high-resolution second measuring device 28, the measuring

devices

24, 28 acting via the same switch lever on the measuring mechanism of the indicating device 50, which converts the stroke into a rotary movement of the pointer 58.

The high accuracy of the second measuring device 28 is compared with a density monitor known from the company manual cited at the outset.

As long as the reference gas filled in the reference chamber of the second measuring device 28 has a higher pressure than the filling in the system 16, the force flow via the second measuring device 28 is first interrupted.

The switching lever is actuated only by the first measuring device 24, which first measuring device 24 comprises a first measuring bellows 40, a driver 54 between the switching lever and the low-pressure bottom 46, the low-pressure bottom 46 and an upper stop 52 for low pressure. Thus, the switch lever is pushed upward by the first measuring device 24.

When the system gas 18 reaches the same pressure as the reference gas 26 in the reference chamber or a higher pressure than the reference gas 26, the reference chamber contracts and a force flow is generated via the actuator 54 towards the switch lever. The first measuring device 24 is pulled so that the switch lever continues to move upwards and reaches the region of the second pressure range 64. The temperature compensated switching point setting range is displayed at this time.

Specific use examples will be described below.

The second measuring device 28 includes a reference chamber cover 32, a reference chamber outer bellows 36, a reference chamber bottom 34, a reference chamber inner bellows 38, and a driver 54. The reference volume thus formed is filled, for example, at 600kPa rel.

For example, if the system 16 is transported to a destination, a user of the density monitor 10 fills his system 16 with, for example, 200kPa rel. This value (i.e., 200kPa rel.) is displayed on the display area of the indicating device 50, and in particular on the scale 60 of the density monitor 10. Once the user has installed his system at the destination, the system is filled with system gas pressure (e.g., 680kpa. During filling, the readable pressure on the display area 50 is increased to 600kPa rel by the first measuring device 24, whereupon the pressure is reached by the reference gas 26 filled by the second measuring bellows 36 with the same pressure counter. As soon as the pressure in the second gas chamber 20 is higher than the pressure in the reference chamber (reference gas 26), the reference chamber bottom 34 is pushed upwards by the drive 54 and the switch lever will take the stroke of the second measuring device 28, which second measuring device 28 can also be referred to as a high resolution reference chamber measuring mechanism, by pulling along the first measuring device 24.

Fig. 6 shows another preferred design of the density monitor 10. The first measuring device 24 has a pressure membrane 68 instead of the first measuring bellows 40. In contrast to the design variants shown in fig. 1 to 5, instead of an integrated low-pressure bellows, i.e. the first measuring bellows 40, a pressure membrane 68 is used, which pressure membrane 68 also measures relative to the atmosphere. Instead of the stroke of the low pressure bellows, the stroke of the pressure membrane 68 is used to assume the first pressure range 62 or the low pressure range. The mechanical coupling and the operating principle are the same as in the design variants shown in fig. 1 to 5.

Fig. 7 shows another preferred design of the density monitor 10. The measuring device 24 has a tubular spring 70 instead of the first measuring bellows 40. Two measuring devices, namely a first measuring device 24 and a second measuring device 28, the first measuring device 24 comprising a tubular spring 70 which measures in relation to one another, the second measuring device 28 being mechanically coupled via the measuring mechanism 66 (in particular comprising a driver segment).

As long as the reference gas filled in the second measuring device 28 has a higher pressure than the filling in the system 16, the force flow through the second measuring device 28 to the measuring means 66 is interrupted first. The measuring means 66 is deflected via the relative measuring system (i.e. the first measuring device 24) only by the tubular spring 70 and the display on the scale 60 takes place via the radial driver section of the measuring means 66. As soon as the system gas has reached the same pressure or a higher pressure than the reference chamber, the reference chamber contracts and a stroke movement, in particular a translational stroke movement, is generated by means of a switching rod acting on an axial drive of the measuring means 66. For this purpose, the drive element 48, which is designed as a switching lever, can be coupled to the second separating element 35 of the second measuring device 28. Due to the higher sensitivity of the second measuring device 28, the first measuring device 24 is overruled and the force flow of the tubular spring 70 to the measuring organ 66 is interrupted. In other words, the low pressure measurement system is overridden due to the higher sensitivity of the reference chamber measurement system and the force flow of the tubular spring 70 to the measurement mechanism 66 is interrupted. The second measuring device 28 therefore acts on the measuring means 66 only in the high-resolution region of the main scale, i.e. in the temperature-compensated switching point setting range or second pressure range 64. In this case, the tubular spring 70 is in particular fluidically coupled to the gas chamber 20. In particular, the tubular spring 70 is partially arranged within the gas chamber 20.

Specific exemplary embodiments will be described in more detail below.

The second measuring device 28, consisting of the reference chamber cover 32, the outer bellows 36, which may also be referred to as outer reference chamber bellows, the reference chamber bottom 34, the inner bellows 38, which may also be referred to as inner reference chamber bellows, and the actuator 54 switch lever, is filled at an absolute pressure of 600 kPa. While in transit, the customer fills the system at 200kPa rel. Due to the mechanical coupling with the measuring means 66, a value of 200kPa rel is now shown on the scale 60 of the display area of the density monitor 10 by means of the first measuring device 24, which first measuring device 24 can also be referred to as an associated tubular spring measuring system. Once the customer has installed his system 16 at the destination, he fills the system with his system gas pressure at 680kPa absolute. During filling, the readable pressure on the indicator 50 is increased to 600kPa by a tubular spring measurement system. Up to now, the reference chamber, which has been filled with the same pressure, is opposite to this pressure. As soon as the system pressure is higher than the pressure in the reference chamber, the compression of the second measuring device 28 (which may also be referred to as reference chamber measuring system) causes an upward deflection of the switch lever and the measuring mechanism 66 is moved via the axial drive. At the same time, the force flow to the tubular spring driver is interrupted. Thus, under the operating conditions of the system 16, the pressure is presented on the scale 60 in absolute value and temperature compensated by the reference chamber measurement system.

Fig. 8 shows another preferred design of the density monitor 10. Instead of the first measuring bellows 40, the first measuring device 24 comprises a pressure cell 72. Unlike the embodiment shown in fig. 7, the tubular spring 70 is replaced by a pressure cell 72, also measured with respect to the atmosphere. The mechanical connection to the measuring device 66 is made axially via a transmission element. For example, the transmission element may be a pin. Preferably, the pressure unit 72 is in particular fluidly coupled to the gas chamber 20. In particular, the pressure unit 72 is partially arranged within the gas chamber 20. For this purpose, a drive element 48 designed as a switching lever can be coupled to the second separating element 35 of the second measuring device 28. The remaining functions are the same as those described in the context of fig. 7. As long as the reference gas filled into the second measuring device 28 has a higher pressure than the filling into the system 16, the force flow through the second measuring device 28 to the measuring means 66 is interrupted first. The measuring device 66 is only deflected by the pressure sensor 72 by the system relative to the measurement, i.e. the first measuring device 24, and is displayed on the scale 60. When the system gas reaches a pressure equal to or greater than the reference chamber, the reference chamber contracts and, via the switching lever, a stroke movement, in particular a translational stroke movement, acting on the axial drive of the measuring means 66 is produced. Due to the higher sensitivity of the second measuring device 28, the first measuring device 24 is overruled and the force flow of the pressure unit 72 to the measuring organ 66 is interrupted. The second measuring device 28 therefore acts on the measuring means 66 only in the high-resolution region of the main scale, i.e. in the temperature-compensated switching point setting range or second pressure range 64.

In summary, the present invention discloses a combined gas density monitor for relative and absolute measurement comprising an indicator.

Two different measuring systems or measuring devices are required to ensure that the entire pressure range is continuously displayed with one scale and one pointer. For the first time, the two measurement systems are mechanically coupled to continuously display the lower pressure relative to the atmosphere, then the operating pressure range of the system is displayed in absolute value and temperature compensated by a single measurement mechanism by a high resolution reference chamber measurement system.

According to a preferred embodiment, the density monitor comprises a combined presentation of the entire pressure range by means of a scale and a display element or an indication element such as an indicator with phosphorescent or fluorescent characters.

According to an advantageous design, the two measuring systems are actuated one after the other in the axial direction from a lower pressure via a high-resolution reference chamber measuring system, with a stroke via the same switching lever to a measuring mechanism which converts the stroke into a rotation of the pointer. The high accuracy of the reference chamber measurement system is maintained.

As long as the reference gas filled into the reference chamber measurement system has a higher pressure than the filling of the system, the force flow through the reference chamber measurement system is interrupted first. The switch lever is pushed upwards only by the low pressure measurement system consisting of low pressure bellows, driver gear lever/low pressure and upper stopper low pressure. When the system gas reaches a pressure equal to or greater than the reference chamber, the reference chamber contracts and a force flow to the switch lever is generated via the actuator shift lever/low pressure. And pulling the low-voltage measuring system to further move the switch rod upwards to reach a high-resolution main scale area, namely the temperature compensation switch point setting range.

In contrast to this design variant, in a further alternative embodiment, a pressure membrane can be used instead of an integrated low-pressure bellows, which is also measured with respect to the atmosphere. Instead of the stroke of the low pressure bellows, the stroke of the pressure diaphragm is used to indicate the low pressure range. The mechanical coupling and the working principle remain unchanged.

In another alternative embodiment, a tubular spring is used for the deeper or lower pressure range. The two measurement systems, i.e. the tubular spring for relative measurement and the reference chamber measurement system, are mechanically coupled together via a specific measurement mechanism comprising a radial driver section. As long as the reference gas filled into the reference chamber measuring system has a higher pressure than the filling in the system, the force flow through the reference chamber measuring system to the measuring means is interrupted first. The measuring device is deflected only by the tubular spring via the system relative measurement and is displayed on a scale via the radial drive section of the measuring device. When the system gas reaches a pressure equal to or greater than the reference chamber, the reference chamber contracts and, via the switching rod, a translatory stroke movement is generated which acts on the axial drive of the measuring mechanism. Due to the higher sensitivity of the reference chamber measuring system, the low pressure measuring system is overruled and the force flow of the tubular spring to the measuring mechanism is interrupted. The reference chamber measuring system therefore acts on the measuring means only in the high resolution region of the main scale, i.e. in the temperature-compensated switching point setting range.

The reference chamber measuring system consists of a reference chamber cover, an outer reference chamber corrugated pipe, a reference chamber bottom, an inner reference chamber corrugated pipe and a driving switch rod, and the filling pressure is 600kPa (absolute pressure). During shipping, the customer fills the system at 200kPa rel. Due to the mechanical coupling with the measuring mechanism, the indicator of the density monitor now displays a value on a scale, 200kPa rel., by the associated tubular spring measuring system. Once the customer has installed his system at the destination, he fills it with his system gas pressure at 680kPa absolute. During the filling process, the readable pressure on the display 15 is raised to 600kPa abs by a tubular spring measurement system. Up to now, the reference chamber filled with the same pressure is opposite to the pressure. As soon as the system pressure is higher than the pressure in the reference chamber, the compression of the reference chamber measuring system causes the switch lever to be deflected upwards, the measuring mechanism being moved by the axial drive, while the force flow to the tubular spring drive is interrupted. Thus, in the operating state of the system, the pressure is shown in absolute value and is temperature compensated by the reference chamber measurement system.

The two measuring systems, the tubular spring for relative measurement and the reference chamber measuring system are mechanically coupled together by a measuring mechanism, which comprises in particular a radial drive section. As long as the reference gas filled into the reference chamber measuring system has a higher pressure than the filling in the system, the force flow through the reference chamber measuring system to the measuring means is interrupted. The measuring device is deflected by the tubular spring only by relative measurement by the system and is displayed on a scale by the radial drive element of the measuring device. When the system gas reaches a pressure equal to or greater than the reference chamber, the latter contracts and a translatory stroke movement is produced by means of a switching rod acting on an axial drive of the measuring mechanism. Due to the higher sensitivity of the reference chamber measuring system, the low pressure measuring system is overruled and the force flow of the tubular spring to the measuring mechanism is interrupted. The reference chamber measuring system therefore acts on the measuring means only in the high resolution region of the main scale, i.e. in the temperature-compensated switching point setting range.

In another alternative embodiment, a separate pressure membrane or pressure cell is used for the low pressure range. Unlike the design variant comprising a tubular spring, a pressure cell is used instead of a tubular spring, which is also measured with respect to the atmosphere. The mechanical coupling with the measuring mechanism takes place axially via a second drive (e.g. a pin). All other functions remain unchanged.

List of reference numerals

10 Density monitor

12 measuring device

14 pressure connector

16 system

18 system gas

20 gas chamber

22 sensor housing

24 first measuring device

26 reference gas

28 second measuring device

30 second measuring bellows

32 reference chamber cover

34 base of reference chamber

35 second separating element

36 external corrugated pipe

38 inner corrugated pipe

40 first measuring bellows

42 low pressure bellows

44 first separation element

46 low pressure bottom

48 drive element

50 indicating device

52 stop

54 actuator

56 Density monitor casing

58 pointer

60 scale

62 first pressure range

64 second pressure range

66 measuring mechanism

68 pressure membrane

70 tubular spring

72 pressure unit

Claims

1. A density monitor (10) for monitoring the density of a gas in a gas cell (20), comprising:

-a measuring device (12) having a first measuring device (24) and a second measuring device (28), the first measuring device (24) and the second measuring device (28) being coupled together, wherein

-the first measuring device (24) is designed for measuring a first pressure range (62) relative to the atmosphere, wherein

-the second measuring device (28) is designed for measuring a second pressure range (64) having an absolute value higher than the first pressure range (62);

-indicating means (50) designed to display said first pressure range (62) and said second pressure range (64); and

-a movable drive element (48) designed for driving the indicating means, wherein at least one of the two measuring devices (24; 28) is designed for moving the drive element (48) for driving the indicating means (50), wherein

-the indicating device (50) comprises an indicating element (58), wherein the indicating element (58) is designed for indicating two pressure ranges (62, 64).

2. Density monitor (10) according to claim 1,

characterized in that the second measuring device (28) is also designed to measure the second pressure range (64) in a temperature-compensated manner.

3. Density monitor (10) according to claim 1 or 2,

characterized in that the second measuring device (28) comprises a second movable separating element (35), the second movable separating element (35) being designed for separating a closed reference volume to be filled with a reference pressure from the gas chamber (20), the second separating element (35) being arranged on a second measuring bellows (30) separating the reference volume from the gas chamber (20).

4. Density monitor (10) according to claim 3,

characterized in that the first measuring device (24) comprises a first movable separating element (44), which first movable separating element (44) is designed for separating the gas chamber (20) from another space, wherein the first movable separating element (44) is arranged on a first measuring bellows (40) which separates the gas chamber (20) from the other space, wherein the first separating element (46) and the second separating element (35) are movable relative to each other in a limited manner by a stop (52) such that they are movable relative to the other separating element to an extent limited by the stop (52).

5. Density monitor (10) according to any of claims 1 to 3,

characterized in that the first measuring device (24) comprises a pressure membrane (68) for measuring the first pressure range (62).

6. Density monitor (10) according to claim 5,

characterized in that the pressure membrane (68) is designed for driving the display device (50), in particular driving the display device (50) by means of a stroke of the pressure membrane (68).

7. Density monitor (10) according to any of claims 1 to 3,

characterized in that the first measuring device (24) comprises a tubular spring (70) for measuring the first pressure range (62).

8. Density monitor (10) according to claim 7,

characterized in that the pinion of the indicating device (50) is coupled with the tubular spring (70) such that when measuring the first pressure range (62), a radial movement is transmitted to the indicating device (50), which radial movement is converted into a rotational movement of the indicating element (58) to indicate the first pressure range (62).

9. Density monitor (10) according to any of claims 1 to 3,

characterized in that the first measuring device (24) comprises a pressure unit (72) for measuring the first pressure range (62).

10. Density monitor (10) according to claim 9,

characterized in that the display device (50) comprises a transmission element designed to receive the vertical movement of the pressure unit (72) and to convert it into a rotational movement of the indicating element (58) in order to indicate the first pressure range (62).

11. Density monitor (10) according to any of the preceding claims,

characterized in that the indicating means (50) further comprises a display area with characters and/or graduations (60), wherein the indicating elements (58) and/or graduations (60) and/or characters comprise phosphorescent or fluorescent material.